ASoC: codecs: wcd937x: Drop unused buck_supply

Last user of wcd937x_priv->buck_supply was removed in
commit 216d041 ("ASoC: codecs: wcd937x: Remove separate handling
for vdd-buck supply").

Fixes: 216d041 ("ASoC: codecs: wcd937x: Remove separate handling for vdd-buck supply")
Cc: stable@vger.kernel.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20250526-b4-b4-asoc-wcd9395-vdd-px-fixes-v1-2-0b8a2993b7d3@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: krzk

sound/soc/codecs/wcd937x.c

@@ -91,7 +91,6 @@ struct wcd937x_priv {
 	struct regmap_irq_chip *wcd_regmap_irq_chip;
 	struct regmap_irq_chip_data *irq_chip;
 	struct regulator_bulk_data supplies[WCD937X_MAX_BULK_SUPPLY];
-	struct regulator *buck_supply;
 	struct snd_soc_jack *jack;
 	unsigned long status_mask;
 	s32 micb_ref[WCD937X_MAX_MICBIAS];